Measurement of Born Cross Sections and Effective Form Factors of $e^+e^-\to Ω^{-}\barΩ^{+}$ from$\sqrt{s}$ = 3.7 to 4.7 GeV

TL;DR

This study measures the energy-dependent Born cross sections for $e^+e^-\to \Omega^-\bar{\Omega}^+$ and the time-like electromagnetic form factor $|G_{\rm eff}(s)|$ of the $\Omega^-$ using 22.7 fb$^{-1}$ of BESIII data collected at 34 center-of-mass energies from $\sqrt{s}=3.7$ to $4.7$ GeV. A single-baryon tagging method is employed to reconstruct $\Omega^-$ and infer the recoil $\Omega^+$, with cross sections computed from corrected yields and efficiencies, and $|G_{\rm eff}(s)|$ derived from the measured cross sections through standard form-factor relations in the time-like region. Clear $\Omega^-\bar{\Omega}^+$ signals appear at $\sqrt{s}=3.77$ and 4.17 GeV, with a hint of structure near 4.22 GeV but no definitive resonant interpretation; the measured EFFs agree with covariant spectator quark model predictions and with CLEO-c within uncertainties. These results constrain the electromagnetic structure and production dynamics of $\Omega^-$ and provide valuable input for theoretical models of SU(3) baryons in the time-like region.

Abstract

Using $e^+e^-$ collision data corresponding to an integrated luminosity of 22.7 fb$^{-1}$, collected at center-of-mass energies between 3.7 and 4.7 GeV with the BESIII detector at the BEPCII storage ring, we measure the energy-dependent Born cross sections of $e^+e^-\to Ω^{-}\barΩ^+$ and the effective form factors of the $Ω^-$ baryon. The analysis employs a single baryon tagging method, and the results are consistent with theoretical predictions, providing critical constraints on the electromagnetic structure of the $Ω^-$ hyperon. No significant signal of charmonium or charmonium-like states decaying to $Ω^{-}\barΩ^+$ is observed in the investigated energy range.

Figures (3)

• Figure 1: Distribution of $RM^{\rm cor}(K^-\Lambda)$ versus $M^{\rm cor}(K^-\Lambda)$ of the accepted candidates from all thirty-four c.m. energies, where the black box shows the signal region, and the red boxes denote the selected sideband regions.
• Figure 2: The measured $e^+e^-\to \Omega^-\bar{\Omega}^+$ BCSs from 3.7 GeV to 4.7 GeV, where the uncertainties are statistical. The red and blue points with error bars are the results obtained in this work and by CLEO-c PRD96-092004, respectively.
• Figure 3: Comparison of the measured EFFs and the theoretical prediction. The black points with error bars are the results of this work. The blue points with error bars are the CLEO-c measurements PRD96-092004, where $G_{\text{E0}}$ is assumed to be zero. The red band indicates the theoretical prediction, in which the red line denotes the predicted central value and its boundaries marks the upper and lower limits of the theoretical error PRD-074018.